Purified sulfonated organophosphorus compounds and catalysis of organic reactions therewith

ABSTRACT

Water-soluble sulfonated organophosphorus compounds are purified by at least partially removing contaminating sulfite values therefrom, by decreasing the pH of a solution of such sulfonated organophosphorus compounds to a value of less than or equal to 4, and maintaining the pH of the solution at this value of 4 or less for such period of time as to reduce the weight concentration of sulfite in the solution to less than 100 ppm; the organophosphorus compounds thus purified are well suited for the two-phase cocatalysis of a wide variety of organic reactions.

CROSS-REFERENCE TO PRIORITY/PCT APPLICATIONS

[0001] This application claims priority under 35 U.S.C. § 119 ofFR-98/16586, filed Dec. 23, 1998, and is a continuation ofPCT/FR99/03234, filed Dec. 21, 1999 and designating the United States(published in the French language on Jul. 6, 2000 as WO 00/39134; thetitle and abstract were also published in English), both herebyexpressly incorporated by reference.

CROSS-REFERENCE TO COMPANION APPLICATIONS

[0002] Copending applications Ser. No. ______ [Attorney Docket No.022701-933] and Serial No. ______ [Attorney Docket No. 022701-935], bothfiled Jun. 22, 2001, both assigned to the assignee hereof, and both alsohereby expressly incorporated by reference.

BACKGROUND OF THE INVENTION

[0003] 1. Technical Field of the Invention

[0004] The-present invention relates to the preparation/purification ofwater-soluble sulfonated organophosphorus compounds which areparticularly well suited as two-phase catalysts for a variety of organicreactions.

[0005] 2. Description of the Prior Art

[0006] Organophosphorus compounds are particularly important as ligandsfor transition metal elements to prepare catalytic systems for variousorganic reactions such as carbonylation, hydroformylation,hydrocyanation and the isomerization of olefinic compounds.

[0007] Such catalytic systems are generally employed in reactionsinvolving a single phase and, thus, an occasionally complex step ofseparation and recovery of the catalyst is required.

[0008] In the early 1970s, water-soluble compounds able to formcomplexes with metal elements in the oxidation state of zero wereproposed as catalysts. These water-soluble compounds generally belong tothe family of organophosphorus compounds comprising at least onesulfonate group. Thus, F. Joes and M. T. Beck, in an article publishedin React. Kim. Catal. Letters, 2, 257 (1975), and Bawoski et al., in anarticle published in the review Nouv. J. Chem., 2, 137 (1978), describea water-soluble monosulfonated triphenylphosphine which cannot beextracted using organic solvents.

[0009] The synthesis of these materials allowed the development of anovel method of catalysis referred to as two-phase catalysis.Specifically, the catalyst, i.e., transition metal elements complexedwith water-soluble organophosphorus compounds, is present in an aqueousphase while the reagents are in an organic phase. Stirring andemulsification of the medium gives efficient catalysis. At the end ofthe reaction, the catalyst is recovered by simple separation bydecantation of the two phases.

[0010] Rhône-Poulenc developed this technique for carrying out severalimportant organic reactions such as the hydroformylation of olefins forthe production of aldehydes, as described in FR-2,505,322 andFR-2,541,675. Another important application of this catalytic system,described, in particular, in FR-2,338,253 and FR-2,366,237, relates tothe hydrocyanation reaction of olefins and the isomerization of thenitrites obtained, for example for the synthesis of adiponitrile, whichis a major chemical intermediate for the manufacture of polyamidemonomers.

[0011] Considerable research is nonetheless ongoing to improve thecost-effectiveness of these processes, in particular by increasing thecycle time and the lifetime of the catalytic system, as well as reducingthe consumption of catalyst per quantity of adiponitrile produced.

[0012] Over the course of this research, degradation of thewater-soluble sulfonated organophosphorus compounds has been observed.

SUMMARY OF THE INVENTION

[0013] Accordingly, a major object of the present invention is theprovision of unique water-soluble sulfonated organophosphorus ligandswhich are resistant to degradation, and more stable two-phase catalyticsystems comprised thereof.

[0014] Briefly, the present invention features carrying out organicreactions by two-phase catalysis, the media of reaction comprising anorganic phase containing the reagents and the reaction products, anaqueous phase comprising a catalyst and a water-soluble sulfonatedorganophosphorus compound, wherein said water-soluble sulfonatedorganophosphorus compound has been purified via removal of contaminatingsulfite compounds or radicals therefrom.

DETAILED DESCRIPTION OF BEST MODE AND SPECIFIC/PREFERRED EMBODIMENTS OFTHE INVENTION

[0015] More particularly according to the present invention, in apreferred embodiment thereof, the sulfonated organophosphorus compoundsthus purified have a weight concentration of sulfite of less than 100ppm, preferably less than 50 ppm.

[0016] In another embodiment of this invention, the removal of sulfitesis attained by converting same into sulfurous gas.

[0017] Exemplary organic reactions catalyzed via two-phase catalysis arehydroformylation, carbonylation, oxidation, isomerization andhydrocyanation reactions, in particular of unsaturated compounds.

[0018] In one preferred embodiment of the present invention, thehydrocyanation of organic compounds containing at least one ethylenicdouble bond is carried out to prepare nitrile compounds such asadiponitrile, for the synthesis of lactam, amino acid or amine monomersfor the production of polyamides. This synthetic process, in particular,comprises a hydrocyanation of 3-pentenenitrile into adiponitrile, forwhich the catalyst comprising a sulfite-freed organophosphine inaccordance with the invention as a component thereof is especiallysuitable.

[0019] Thus, in such an application, the lifetime of the catalyst can begreatly improved. This improvement is observed, in the case of thehydrocyanation of organic compounds comprising more than one ethylenicdouble bonds and in particular dienes, both for the hydrocyanationreaction of the first ethylenic bond and in that of the second ethylenicbond.

[0020] The process of the invention permits conducting thehydrocyanation of butadiene for the synthesis of adiponitrile with acatalyst based on water-soluble sulfonated organophosphorus ligands andon at least one metal element in oxidation state zero, with aconsumption of catalyst per kg of adiponitrile produced which ismarkedly lower than that existing when using a catalyst or a ligandwhich has not been subjected to removal of sulfites.

[0021] In another preferred embodiment of the invention, removal of thesulfites contained in the water-soluble sulfonated organophosphoruscompound is obtained by lowering the pH of the solution oforganophosphorus compounds to a value of less than or equal to 4 andmaintenance of such solution at a pH of less than or equal to 4 until asulfite concentration in the solution of less than 100 ppm is attained.

[0022] Assay of the sulfite compounds in the solution is carried out,for example, by ionic chromatography.

[0023] The lowering of the pH of the solution can be accomplished by anysuitable means. However, in another preferred embodiment of theinvention, this lowering is accomplished by addition of a stronginorganic or organic acid in pure form or, more preferably, in solution.

[0024] The acidic solution can be a concentrated or dilute solution.

[0025] Exemplary acids which are suitable according to the presentinvention, representative are those acids having, for example, a pKa ofless than or equal to 4, the corresponding anhydrides and more generallyany compound which is chemically inert with respect to theorganophosphorus compound and which can lower the pH of a solution.

[0026] Exemplary such acids are sulfuric acid, hydrochloric acid,trifluoroacetic acid, para-toluenesulfonic acid, perchloric acid andnitric acid.

[0027] Moreover, the solution of water-soluble sulfonatedorganophosphorus compounds is preferably an aqueous solution. However,solutions using water/alcohol mixtures as solvent are also suitable. Thealcohol can be replaced with any water-miscible solvent.

[0028] In another embodiment of the invention, the solution ismaintained at a pH of less than or equal to 4, at a temperature below100° C. and advantageously ranging from 40° C. to 90° C.

[0029] The sulfurous gas produced by converting the sulfites is, in onepreferred embodiment of the invention, removed from the reaction mediumby entrainment with a carrier fluid. This carrier fluid is preferablynonoxidizing. Thus, carrier fluids which are suitable for the inventionare, for example, nitrogen, carbon dioxide, water vapor, rare or inertgases, and oxygen-depleted air.

[0030] The water-soluble sulfonated organophosphorus compounds which aresuitable for treatment according to the process of the invention andwhich are useful as ligands in the processes of two-phase catalysis aregenerally the sulfonated organophosphorus compounds prepared via one ormore sulfonation steps as described in the article published in J. Chem.Soc., pages 276-288 (1958) or in GB-1,066,261. These can also beprepared by reacting sodium p-chlorobenzenesulfonate withdiphenylchlorophosphine, as described in the article by H. Schindlbauer,Monatsch. Chem., 96, pages 2051-2057 (1965).

[0031] Generally, these processes for synthesizing sulfonatedorganophosphorus compounds do not make it possible to obtain a compoundwhich is free of sulfite compounds or radicals. Consequently, in orderto avoid degradation of these compounds during their use as a catalystor a ligand of a catalytic system, it is necessary according to theprocess of the invention to remove these sulfites at least partially.

[0032] Suitable water-soluble sulfonated phosphine compounds accordingto the invention include those described in FR-2,338,253 or in WO97/12857 and EP 0,650,959.

[0033] Thus, suitable phosphines according to this invention have thefollowing structural formula (I):

[0034] in which Ar₁, Ar₂ and Ar₃, which may be identical or different,are each an aryl radical; Y₁, Y₂ and Y₃, which may be identical ordifferent, are each an alkyl radical having from 1 to 4 carbon atoms, analkoxy radical having from 1 to 4 carbon atoms, a halogen atom, a CNgroup, an NO₂ group, an OH group, an NR₁R₂ radical, wherein R₁ and R₂,which may be identical or different, are each an alkyl radical havingfrom 1 to 4 carbon atoms; M is an inorganic or organic cationic residueselected, such that the compound of formula (I) is soluble in water,from the group consisting of H⁺, cations derived from alkali metals oralkaline earth metals, N(R₃R₄R₅R₆)⁺, wherein R₃, R₄, R₅ and R₆, whichmay be identical or different, are each an alkyl radical having from 1to 4 carbon atoms or a hydrogen atom, and other metal cations, thebenzenesulfonic acid salts of which are soluble in water; m₁, m₂ and m₃which may be identical or different, are each an integer ranging from 0to 5; and n₁, n₂ and n₃, which may be identical or different, are eachan integer ranging from 0 to 3, at least one of these being equal to orgreater than 1.

[0035] Exemplary metals, the benzenesulfonic acid salts of which aresoluble in water, include lead, zinc and tin.

[0036] By the expression “soluble in water” is generally intended acompound soluble to at least 0.01 g per liter of water.

[0037] Preferred phosphines of formula (I) are those in which:

[0038] Ar₁, Ar₂ and Ar₃ are phenyl radicals;

[0039] Y₁, Y₂ and Y₃ are alkyl radicals having from 1 to 2 carbon atoms,or alkoxy radicals having from 1 to 2 carbon atoms;

[0040] M is a cation selected from the group consisting of H⁺, cationsderived from Na, K, Ca and Ba , NH ₄ ⁺, and tetramethylammonium,tetraethylammonium, tetrapropylammonium and tetrabutylammonium cations;

[0041] m₁, m₂ and m₃ are integers ranging from 0 to 3; and

[0042] n₁, n₂ and n₃ are integers ranging from 0 to 3, at least one alsobeing greater than 1.

[0043] The more particularly preferred phosphines are the sodium,potassium, calcium, barium, ammonium, tetramethylammonium andtetraethylammonium salts of mono(sulfophenyl)diphenylphosphine,di(sulfophenyl)phenylphosphine and tri(sulfophenyl)phosphine, in whichthe SO₃ groups are preferably in the meta-position.

[0044] Exemplary phosphines of formula (I) according to the process ofthe invention are alkali metal or alkaline earth metal salts, ammoniumsalts, or quaternary ammonium salts of(3-sulfo-4-methylphenyl)di(4-methylphenyl)phosphine,(3-sulfo-4-methoxyphenyl)di(4-methoxyphenyl)phosphine,(3-sulfo-4-chlorophenyl)di(4-chlorophenyl)phosphine,di(3-sulfophenyl)phenylphosphine, di(4-sulfophenyl)phenylphosphine,di(3-sulfo-4-methylphenyl)(4-methylphenyl)phosphine,di(3-sulfo-4-methoxyphenyl)(4-methoxyphenyl)phosphine,di(3-sulfo-4-chlorophenyl)(4-chlorophenyl)phosphine,tri(3-sulfophenyl)phosphine, tri(4-sulfophenyl)phosphine,tri(3-sulfo-4-methylphenyl)phosphine,tri(3-sulfo-4-methoxyphenyl)phosphine,tri(3-sulfo-4-chlorophenyl)phosphine,(2-sulfo-4-methylphenyl)(3-sulfo-4-methylphenyl)(3,5-disulfo-4-methylphenyl)phosphineor (3-sulfophenyl)(3-sulfo-4-chlorophenyl)(3,5-disulfo-4-chlorophenyl)phosphine.

[0045] A mixture of these phosphines can of course be employed, inparticular a mixture of mono-, di- and tri-meta-sulfonated phosphines.

[0046] Monodentate and bidentate phosphines having the followingstructural formulae (II) and (III) are also suitable according to thepresent invention:

[0047] in which Ar1 and Ar2, which may be identical or different, areeach aryl radicals or substituted such aryl radicals bearing one or moresubstituents, such as alkyl or alkoxy radicals having from 1 to 4 carbonatoms, halogen atoms, hydrophilic groups, such as —COOM, —SO₃M or —PO₃M,wherein M is an inorganic or organic cationic residue selected fromamong hydrogen, cations derived from alkali metals or alkaline earthmetals, ammonium cations —N(R)₄, wherein the radicals R, which may beidentical or different, are each a hydrogen atom or an alkyl radicalhaving from 1 to 4 carbon atoms, and other cations derived from metals,the arylcarboxylic acid, arylsulfonic acid or arylphosphonic acid saltsof which are soluble in water, —N(R)₄, wherein the radicals R, which maybe identical or different, are each a hydrogen atom or an alkyl radicalhaving from 1 to 4 carbon atoms, or —OH; Ar₃ is a substituted arylradical bearing one or more substituents, such as alkyl or alkoxyradicals having from 1 to 4 carbon atoms, halogen atoms, hydrophilicgroups, such as —COOM or -PO₃M, wherein M is an inorganic or organiccationic residue selected from among hydrogen, cations derived fromalkali metals or alkaline earth metals, ammonium cations —N(R)₄, whereinthe radicals R, which may be identical or different, are each a hydrogenatom or an alkyl radical having from 1 to 4 carbon atoms, and othermetal cations, the arylcarboxylic acid or arylphosphonic acid salts ofwhich are soluble in water, N(R)₄, wherein the radicals R, which may beidentical or different, are each a hydrogen atom or an alkyl radicalhaving from 1 to 4 carbon atoms, or —OH, with the proviso that at leastone of the substituents of Ar₃ is a hydrophilic group as defined above;a is 0 or 1; b is 0 or 1; c is an integer ranging from 0 to 3; D is analkyl radical, a cycloalkyl radical or an alkyl or cycloalkyl radicalsubstituted by one or more substituents, such as an alkoxy radicalhaving from 1 to 4 carbon atoms, a halogen atom, a hydrophilic group,such as —COOM, —SO ₃M or —PO₃M, wherein M is an inorganic or organiccationic residue selected from among hydrogen, cations derived fromalkali metals or alkaline earth metals, ammonium cations —N(R)₄, whereinthe radicals R, which may be identical or different, are each a hydrogenatom or an alkyl radical having from 1 to 4 carbon atoms, and othermetal cations, the arylcarboxylic acid, arylsulfonic acid orarylphosphonic acid salts of which are soluble in water, —N(R)₄, whereinthe radicals R, which may be identical or different, are each a hydrogenatom or an alkyl radical having from 1 to 4 carbon atoms, or —OH; d isan integer ranging from 0 to 3; and the sum (a+b+c+d) is equal to 3; and

[0048] in which Ar1, Ar2 and D are as defined above for the formula(II); a, b, e, and f are each 0 or 1; d and g are each an integerranging from 0 to 2; the sum (a+b+d) is equal to 2; the sum (e+f+g) isequal to 2; and L is a single valency bond or a divalenthydrocarbonaceous radical, such as an alkylene radical, a cycloalkyleneradical, an arylene radical, or a radical deriving from a heterocyclecomprising one or two oxygen, nitrogen or sulfur atoms in the ring,these various cyclic radicals being bonded directly to one of thephosphorus atoms or both phosphorus atoms or being bonded to one of thephosphorus atoms or to both via a linear or branched alkylene radicalhaving from 1 to 4 carbon atoms, with the proviso that the ring or ringswhich are optionally moieties of the divalent radical L may comprise oneor more substituents, such as an alkyl radical having from 1 to 4 carbonatoms.

[0049] Exemplary phosphines of structural formula (II) includetris(hydroxymethyl)phosphine, tris(2-hydroxyethyl)phosphine,tris(3-hydroxypropyl)phosphine, tris(2-carboxymethyl)phosphine, thesodium salt of tris(3-carboxyphenyl)phosphine,tris(3-carboxyethyl)phosphine, tris(4-trimethylammoniophenyl)phosphineiodide, the sodium salt of tris(2-phosphonoethyl)phosphine orbis(2-carboxyethyl)phenylphosphine.

[0050] And exemplary phosphines of structural formula (III) include thesodium salt of 2,2′-bis[di(sulfophenyl)phosphino]-1, 1′-binaphthyl, thesodium salt of 1,2-bis[di(sulfophenyl)phosphinomethyl]cyclobutane(CBDTS), 1,2-bis(dihydroxymethylphosphino)ethane,1,3-bis(dihydroxymethylphosphino)propane, or the sodium salt of 2,2′-bis[di(sulfophenyl)phosphinomethyl] -1,1′-binaphthyl.

[0051] Certain of the water-soluble phosphines of formulae (I) to (III)are commercially available.

[0052] For the preparation of the others, reference is made to thegeneral or specific processes for the synthesis of phosphines describedin the general literature, such as Houben-Weyl, Methoden der organischenChemie, “organische Phosphor Verbindungen” [Methods of OrganicChemistry, “Organic Phosphorus Compounds”], Part 1(1963).

[0053] Lastly, for the preparation of water-soluble derivatives whichhave not been described, starting from phosphines not comprisingwater-soluble substituents described above, one or more of thesehydrophilic substituents are introduced. Thus, sulfonate groups, forexample, may be introduced by the reaction of SO₃ in sulfuric acid.Carboxylate, phosphonate and quaternary ammonium groups can likewise beintroduced via the usual chemical techniques for this type of synthesis.

[0054] Other water-soluble sulfonated organophosphorus compounds whichare suitable are the compounds BISBIS, NORBOS and BINAS described in thearticle by Boy Cornils and Emile G. Kuntz, published in Journal ofOrganometallic Chemistry, No. 502 (1995) pp. 177-186. Also suitable arethe water-soluble furylphosphine compounds described in French patentapplication No. 98/06559, filed May 20, 1998, assigned to the assigneehereof.

[0055] As indicated above, the subject sulfite-freed organophosphoruscompounds are particularly useful as components of catalysts comprisinga transition metal element selected, for example, from the groupconsisting of nickel, cobalt, iron, ruthenium, rhodium, palladium,osmium, iridium, platinum, copper, silver, gold, zinc, cadmium andmercury in variable oxidation states.

[0056] It should be appreciated that, in these catalysts, generally,rhodium is in oxidation state (I), ruthenium is in oxidation state (II),platinum is in oxidation state (I), palladium is in oxidation state(II), osmium is in oxidation state (0), iridium is in oxidation state(0) and nickel is in oxidation state (0).

[0057] In order to further illustrate the present invention and theadvantages thereof, the following specific examples are given, it beingunderstood that same are intended only as illustrative and in nowiselimitative.

EXAMPLE 1

[0058] 19.2 kg of an aqueous solution containing 30% by weight of thesodium salt of triphenylphosphine trisulfonate and initially containing1,540 ppm of sulfites (pH=6.2) were introduced into a 20 liter reactorstirred with a turbomixer (180 rpm) and fitted with an ascendingcondenser, a nitrogen inlet via a dipping cannula and a bubblercontaining an aqueous sodium hydroxide solution (1 mol/liter). Thissolution was degassed. 222 g of an aqueous sulfuric acid solution at 2mol/liter were then introduced, which provided a pH of 1.8. This mixturewas heated to 80° C. with stirring and under a stream of nitrogen suchas to entrain the sulfurous gas. Assay of the sulfites by ionicchromatography on samples withdrawn every 15 minutes made it possible tomonitor the conversion of the sulfites into sulfur dioxide. After 1 hourat 80° C., the assay in question gave the following result: 80 ppm ofsulfites. After 1 h, 45 minutes, the sulfite content became less than orequal to 40 ppm (detection limit of the ionic chromatography analysis).After 2 hours at 80° C., the mixture was cooled with stirring to roomtemperature. 324 g of an aqueous sodium hydroxide solution at 1mol/liter were then introduced and a sulfite-freed aqueous solution ofTPPTS (pH=5.4) was obtained.

EXAMPLE 2

[0059] 500 cm³ of the sulfite-freed aqueous solution of TPPTS at 30% byweight, of Example 1, were introduced into a 1 liter glassround-bottomed flask fitted with a magnetic stirring bar and anascending condenser. The solution was degassed. 20 g of Ni(cyclooctadiene)₂ were then introduced, with stirring and under a streamof nitrogen, followed by 350 cm³ of pre-degassed orthoxylene. Thismixture was heated at 45° C. for 15 h. After cooling, the two-phasesystem was decanted. About 35 cm³ of the aqueous phase, which had a deepred coloration, were withdrawn and introduced into a 150 cm³ glassreactor fitted with a turbomixer and purged with argon. This aqueousphase was heated to 90° C. and 3.2 cm³ of an aqueous solution of zincchloride at 70% by weight were then added. The mixture was maintained at90° C. with stirring for 48 hours. After cooling to room temperature, asample of the aqueous solution was withdrawn and analysed byphosphorus-31 NMR (nuclear magnetic resonance). The analysis, performedon a Bruker AMX 300 II® spectrometer at a frequency of 121 MHZ,evidenced that the TPPTS contained no TPPTS sulfide (content less thanthe detection limit of the analysis technique, i.e., less than 0.1 mol %of the total phosphorus in solution).

EXAMPLE 3

[0060] 500 cm³ of the aqueous solution of TPPTS at 30% by weight,initially containing 1,540 ppm of sulfites, were introduced into a 1liter glass round-bottomed flask fitted with a magnetic stirring bar andan ascending condenser. The solution was degassed. 20 g ofNi(cyclooctadiene)₂ were then introduced, with stirring and under astream of argon, followed by 350 cm³ of pre-degassed ortho-xylene. Thismixture was heated at 45° C. for 15 h. After cooling, the two-phasesystem was decanted. About 35 cm³ of the aqueous phase, which had a deepred coloration, were withdrawn and introduced into a 150 cm³ glassreactor fitted with a turbomixer and purged with argon. This aqueousphase was heated to 90° C. and 3.2 cm³ of an aqueous solution of zincchloride at 70% by weight were then added. The mixture was maintained at90° C. with stirring at 48 hours. After cooling to room temperature, asample of the aqueous solution was withdrawn and analysed byphosphorus-31 NMR (nuclear magnetic resonance). The analysis inquestion, performed on a Bruker AMX 300 II spectrometer at a frequencyof 121 MHZ, evidence that it contained TPPTS sulfide (peak at 43.7 ppm)to an extent of 4.5 mol % of the total phosphorus in solution.

[0061] While the invention has been described in terms of variousspecific and preferred embodiments, the skilled artisan will appreciatethat various modifications, substitutions, omissions, and changes may bemade without departing from the spirit thereof. Accordingly, it isintended that the scope of the present invention be limited solely bythe scope of the following claims, including equivalents thereof.

What is claimed is:
 1. A process for the purification of water-soluble sulfonated organophosphorus compounds by at least partially removing contaminating sulfite values therefrom, comprising decreasing the pH of a solution of said sulfonated organophosphorus compounds to a value of less than or equal to 4, and maintaining the pH of said solution at this value of 4 or less for such period of time as to reduce the weight concentration of sulfite in said solution to less than 100 ppm.
 2. The process as defined by claim 1, comprising maintaining the pH of said solution at the value of 4 or less for such period of time as to reduce the weight concentration of sulfite in said solution to less than 50 ppm.
 3. The process as defined by claim 1, comprising decreasing the pH of said solution by adding an acidic compound thereto.
 4. The process as defined by claim 3, said acidic compound comprising a strong inorganic or organic acid.
 5. The process as defined by claim 4, said strong acid having a pKa of 4 or less.
 6. The process as defined by claim 5, said strong acid comprising sulfuric acid, hydrochloric acid, trifluoroacetic acid, para-toluenesulfonic acid, perchloric acid, or nitric acid.
 7. The process as defined by claim 1, comprising maintaining the temperature of said solution at less than 100° C.
 8. The process as defined by claim 7, comprising maintaining the temperature of said solution at a value ranging from 40° C. to 90° C.
 9. The process as defined by claim 1, comprising converting contaminating sulfite values into a sulfurous gas and removing said sulfurous gas from said solution.
 10. The process as defined by claim 9, comprising removing said sulfurous gas from said solution by entraining same in a carrier fluid.
 11. The process as defined by claim 10, said carrier fluid comprising nitrogen, carbon dioxide, water vapor, a rare or inert gas, or an oxygen-depleted air.
 12. The process as defined by claim 1, said solution of said sulfonated organophosphorus compound comprising an aqueous or water/alcohol solution.
 13. A water-soluble sulfonated organophosphorus compound containing diminished contaminating amounts of sulfite values, the weight concentration thereof being less than 100 ppm.
 14. A water-soluble sulfonated organophosphorus compound containing diminished contaminating amounts of sulfite values, the weight concentration thereof being less than 50 ppm.
 15. The sulfite-reduced water-soluble sulfonated organophosphorus compound as defined by claim 13, having the structural formula (I):

in which Ar₁, Ar₂ and Ar₃, which may be identical or different, are each an aryl radical; Y₁, Y₂ and Y₃, which may be identical or different, are each an alkyl radical having from 1 to 4 carbon atoms, an alkoxy radical having from 1 to 4 carbon atoms, a halogen atom, a CN group, an NO₂ group, an OH group, an NR₁R₂ radical, wherein R₁ and R₂, which may be identical or different, are each an alkyl radical having from 1 to 4 carbon atoms; M is an inorganic or organic cationic residue selected, such that the compound of formula (I) is soluble in water, from the group consisting of H⁺, cations derived from alkali metals or alkaline earth metals, N(R₃R₄R₅R₆)⁺, wherein R₃, R₄, R₅ and R₆, which may be identical or different, are each an alkyl radical having from 1 to 4 carbon atoms or a hydrogen atom, and other metal cations, the benzenesulfonic acid salts of which are soluble in water; m₁, m₂ and m₃ which may be identical or different, are each an integer ranging from 0 to 5; and n₁, n₂ and n₃, which may be identical or different, are each an integer ranging from 0 to 3, at least one of these being equal to or greater than
 1. 16. The sulfite-reduced water-soluble sulfonated organophosphorus compound as defined by claim 13, having the structural formula (II):

in which Ar1 and Ar2, which may be identical or different, are each aryl radicals or substituted such aryl radicals bearing one or more substituents: alkyl or alkoxy radicals having from 1 to 4 carbon atoms, halogen atoms, the hydrophilic groups —COOM, —SO₃M or —PO₃M, wherein M is an inorganic or organic cationic residue selected from among hydrogen, cations derived from alkali metals or alkaline earth metals, ammonium cations —N(R)₄, wherein the radicals R, which may be identical or different, are each a hydrogen atom or an alkyl radical having from 1 to 4 carbon atoms, and other cations derived from metals, the arylcarboxylic acid, arylsulfonic acid or arylphosphonic acid salts of which are soluble in water, —N(R)₄, wherein the radicals R, which may be identical or different, are each a hydrogen atom or an alkyl radical having from 1 to 4 carbon atoms, or —OH; Ar₃ is a substituted aryl radical bearing one or more of the following substituents: alkyl or alkoxy radicals having from 1 to 4 carbon atoms, halogen atoms, the hydrophilic groups —COOM or —PO₃M, wherein M is an inorganic or organic cationic residue selected from among hydrogen, cations derived from alkali metals or alkaline earth metals, ammonium cations —N(R)₄, wherein the radicals R, which may be identical or different, are each a hydrogen atom or an alkyl radical having from 1 to 4 carbon atoms, and other metal cations, the arylcarboxylic acid or arylphosphonic acid salts of which are soluble in water, N(R)₄, wherein the radicals R, which may be identical or different, are each a hydrogen atom or an alkyl radical having from 1 to 4 carbon atoms, or —OH, with the proviso that at least one of the substituents of Ar₃ is a hydrophilic group as defined above; a is 0 or 1; b is 0 or 1; c is an integer ranging from 0 to 3; D is an alkyl radical, a cycloalkyl radical or an alkyl or cycloalkyl radical substituted by one or more of the following substituents: an alkoxy radical having from 1 to 4 carbon atoms, a halogen atom, a hydrophilic group —COOM, —SO₃M or —PO₃M, wherein M is an inorganic or organic cationic residue selected from among hydrogen, cations derived from alkali metals or alkaline earth metals, ammonium cations —N(R)₄, wherein the radicals R, which may be identical or different, are each a hydrogen atom or an alkyl radical having from 1 to 4 carbon atoms, and other metal cations, the arylcarboxylic acid, arylsulfonic acid or arylphosphonic acid salts of which are soluble in water, —N(R)₄, wherein the radicals R, which may be identical or different, are each a hydrogen atom or an alkyl radical having from 1 to 4 carbon atoms, —OH; d is an integer ranging from 0 to 3; and the sum (a+b+c+) is equal to 3 or having the structural formula (III);

in which Ar1, Ar2 and D are as defined above for the formula (II); a, b, e, and f are each 0 or 1; d and g are each an integer ranging from 0 to 2; the sum (a+b+d) is equal to 2; the sum (e+f+g) is equal to 2; and L is a single valency bond or a divalent hydrocarbonaceous radical, or a radical deriving from a heterocycle comprising one or two oxygen, nitrogen or sulfur atoms in the ring, these various cyclic radicals being bonded directly to one of the phosphorus atoms or both phosphorus atoms or being bonded to one of the phosphorus atoms or to both via a linear or branched alkylene radical having from 1 to 4 carbon atoms, with the proviso that the ring or rings which are optionally moieties of the divalent radical L optionally bear one or more substituents.
 17. In a process for the two-phase catalysis of an organic reaction, wherein the medium of reaction comprises an organic phase containing the reagents and the products of reaction and an aqueous phase containing a catalyst and a water-soluble sulfonated organophosphorus compound cocatalyst, the improvement which comprises, as the cocatalyst therefor, a water-soluble sulfonated organophosphorus compound containing diminished contaminating amounts of sulfite values.
 18. In a process for the two-phase catalysis of an organic reaction, wherein the medium of reaction comprises an organic phase containing the reagents and the products of reaction and an aqueous phase containing a catalyst and a water-soluble sulfonated organophosphorus compound cocatalyst, the improvement which comprises, as the cocatalyst therefor, a water-soluble sulfonated organophosphorus compound containing diminished contaminating amounts of sulfite values as defined by claim
 13. 19. In a process for the two-phase catalysis of an organic reaction, wherein the medium of reaction comprises an organic phase containing the reagents and the products of reaction and an aqueous phase containing a catalyst and a water-soluble sulfonated organophosphorus compound cocatalyst, the improvement which comprises, as the cocatalyst therefor, a water-soluble sulfonated organophosphorus compound containing diminished contaminating amounts of sulfite values as defined by claim
 14. 20. The process as defined by claim 17, said organic reaction comprising a hydroformylation, carbonylation, oxidation, isomerization, or hydrocyanation reaction.
 21. The process as defined by claim 20, said organic reaction comprising the hydrocyanation of an organic compound containing at least one site of ethylenic unsaturation.
 22. The process as defined by claim 21, said organic compound comprising a diolefin or unsaturated nitrile.
 23. The process as defined by claim 17, said catalyst comprising at least one transition metal.
 24. The process as defined by claim 23, said at least one transition metal comprising nickel, cobalt, iron, ruthenium, rhodium, palladium, osmium, iridium, platinum, copper, silver, gold, zinc, cadmium, or mercury.
 25. The process as defined by claim 23, said catalyst further comprising a promoter or dopant metal element.
 26. The purified, sulfite-reduced, water-soluble sulfonated organophosphorus compound product of the process as defined by claim
 1. 